U.S. patent application number 15/123296 was filed with the patent office on 2017-03-16 for heating device for producing carbon fibers.
This patent application is currently assigned to CLARIANT INTERNATIONAL LTD.. The applicant listed for this patent is CLARIANT INTERNATIONAL LTD., Linn High Therm GmbH. Invention is credited to Daniel DECKER, Juergen KUNSTMANN, Horst LINN, Rudolf LINN, Phillip SCHWERDT, Michael WOELKI.
Application Number | 20170073846 15/123296 |
Document ID | / |
Family ID | 52669572 |
Filed Date | 2017-03-16 |
United States Patent
Application |
20170073846 |
Kind Code |
A1 |
DECKER; Daniel ; et
al. |
March 16, 2017 |
HEATING DEVICE FOR PRODUCING CARBON FIBERS
Abstract
A heating device for producing carbon fibers from a
thread-shaped fiber starting material, wherein the heating device
has a central tubular induction heating element through which the
fiber starting material is moved. The tubular induction heating
element is surrounded by thermal insulation. At least one mid- to
high-frequency induction coil is provided outside the thermal
insulation, and an inert gas flows through the central induction
heating element, in particular, for carbonizing and/or graphitizing
the fiber starting material. For energy optimization, a first and a
second tube element is provided on the outer side of the thermal
insulation. The elements are made of material that is transparent
to the induction field of the mid- to high-frequency induction coil
and are spaced apart from one another by an annular gap through
which the inert gas flows.
Inventors: |
DECKER; Daniel; (Liederbach,
DE) ; WOELKI; Michael; (Frankfurt am Main, DE)
; SCHWERDT; Phillip; (Mainz-Kastel, DE) ; LINN;
Horst; (Eschenfelden, DE) ; LINN; Rudolf;
(Hersbruck, DE) ; KUNSTMANN; Juergen; (Bad Soden,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CLARIANT INTERNATIONAL LTD.
Linn High Therm GmbH |
Muttenz
Eschenfelden |
|
CH
DE |
|
|
Assignee: |
CLARIANT INTERNATIONAL LTD.
Muttenz
CH
Linn High Therm GmbH
Eschfelden
DE
|
Family ID: |
52669572 |
Appl. No.: |
15/123296 |
Filed: |
February 27, 2015 |
PCT Filed: |
February 27, 2015 |
PCT NO: |
PCT/EP2015/000457 |
371 Date: |
September 2, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05B 6/108 20130101;
D02J 13/005 20130101; D01F 9/12 20130101; D02J 13/001 20130101;
D01F 9/328 20130101; H05B 6/44 20130101; D01F 9/32 20130101 |
International
Class: |
D01F 9/32 20060101
D01F009/32; D02J 13/00 20060101 D02J013/00; H05B 6/10 20060101
H05B006/10 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 3, 2014 |
DE |
10 2014 003 126.8 |
Claims
1. A heating device for producing carbon fibers from a threadlike
fiber starting material, wherein the heating device comprises a
central tubular induction heating element through which the fiber
starting material is moved, the tubular induction heating element
is surrounded by a thermal insulation, the heating device is an
induction coil outside the thermal insulation and the central
tubular induction heating element receives a flow of inert gas,
wherein a heating source is formed by at least one medium to high
frequency induction coil, and on the outside of the thermal
insulation there are provided a first and a second tube element of
material transparent to the induction field of the induction coil,
which are separated from each other by an annular gap, through
which the inert gas flows.
2. The heating device as claimed in claim 1, wherein gas guiding
elements are provided in the annular gap between the first and the
second tube element.
3. The heating device as claimed in claim 1, wherein the inert gas
is guided in counterflow through the annular gap between the first
and the second tube element and through the central tubular
induction heating element.
4. The heating device as claimed in claim 1, wherein the inert gas
is directed through the central induction heating element in the
one axial direction and at the same time the threadlike fiber
starting material is moved in the opposite direction through the
induction heating element.
5. The heating device as claimed in claim 1, wherein at least one
fiber starting material thread is moved through the central
induction heating element.
6. The heating device as claimed in claim 5, wherein a number of
fiber starting material threads are moved through the central
induction heating element at the same time, the fiber starting
material threads lying spaced apart from each other in one plane or
in several planes.
7. The heating device as claimed in claim 1, wherein the thermal
insulation consists of a carbon fiber felt.
8. The heating device as claimed in claim 1, wherein the thermal
insulation has an inner layer of a carbon fiber felt and an outer
layer of Al.sub.2O.sub.3 fibers or of Al.sub.2O.sub.3/SiO.sub.2
fibers.
9. The heating device as claimed in claim 7, wherein the thermal
insulation is spaced apart from the central tubular induction
heating element by an annular gap through which the inert gas
flows.
10. The heating device as claimed in claim 1, wherein at the two
axially opposite ends of the central tubular induction heating
element and the first and second tube element there is provided a
cover element each time.
11. The heating device as claimed in claim 10, wherein the one
cover element is provided for the diverting of the inert gas from
the annular gap between the first and the second tube element to
the central tubular induction heating element and the other cover
element for the introducing of the inert gas into the annular gap
between the first and the second tube element and for bringing the
inert gas out from the central tubular induction heating
element.
12. The heating device as claimed in claim 10, wherein an air lock
for the threadlike fiber starting material is provided on each of
the two cover elements on the outside.
13. The heating device as claimed in claim 10, wherein the cover
elements are each designed with a cooling device.
14. The heating device as claimed in claim 1, wherein the central
tubular induction heating element consists of carbon
fiber-reinforced carbon, and the carbon fibers used as the
reinforcement are formed by endless fibers.
15. The heating device as claimed in claim 1, wherein at the two
end sections facing away from each other axially in the central
tubular induction heating element there is provided a radiation
shielding perforated disk.
16. The heating device as claimed in claim 1, wherein adjacent to
the two end faces of the thermal insulation facing away from each
other axially there is provided in each case at least one radiation
shielding annular disk.
17. The heating device as claimed in claim 1, wherein at least the
first tube element adjacent to the thermal insulation is provided
with an infrared reflecting coating on the inside, the outside or
both the inside and the outside.
Description
[0001] The invention concerns a heating device for producing carbon
fibers from a threadlike fiber starting material, wherein the
heating device has a central tubular induction heating element,
through which the fiber starting material is moved, the tubular
induction heating element is surrounded by a thermal insulation,
the heating source is an induction coil outside the thermal
insulation, and the central induction heating element receives a
flow of inert gas in particular for the carbonization and/or
graphitization of the fiber starting material.
[0002] U.S. Pat. No. 4,469,925 discloses a heating device for
workpieces of carbon with a first thermal insulation layer of
carbon powder and a second thermal insulation layer of a mixture of
carbon and silicon powder.
[0003] From DE 37 87 582 T2 there is known a carbonization oven
with a thermal insulation, which is composed of a carbon fiber felt
and a ceramic fiber felt. The carbon fiber felt and the ceramic
fiber felt are spaced apart from each other.
[0004] From DE 30 31 303 C2 there is known a heating device for
producing carbon fibers, in which the heating source is formed by a
high frequency induction coil. The thermal insulation consists of
carbon particles having an average grain diameter of 0.5 to 1.5 mm
and an angle of repose of .ltoreq.35.degree.. The carbon particles
are obtained by granulation of soot powder, having an average grain
diameter of around 50 to 300 .mu.m, with a binder and by
carbonization of the binder. The thermal insulation in this known
heating device can consist of a relatively thin layer of carbon
fiber felt and a layer of carbon particles provided around this
felt layer. The carbon fiber felt layer there is, for example, 10
to 15 mm, because it is slightly subject to an induction by the
high frequency generated by the high frequency coil, as is stated
in column 8, lines 45 to 51. The thermal insulation of this known
heating device is provided in a tube of a heat-resistant material,
immediately adjacent to the latter. The tube of the heat-resistant
material is hermetically sealed at its two axially separated ends
by cover elements. One of the two cover elements is fashioned with
a gas inlet and a gas outlet for the inert gas. The inert gas is,
for example, nitrogen, argon, helium or the like.
[0005] This vertically oriented heating device has shortcomings in
regard to its energy balance, although there is no denying that its
energy balance is better than that of a heating device of this kind
which uses an electrical resistance heating instead of a high
frequency induction coil.
[0006] The problem which the invention proposes to solve is to
create a heating device of the kind mentioned above in which the
energy balance is significantly improved by simple design
means.
[0007] This problem is solved according to the invention by the
features of claim 1, i.e., in that the heating source is formed by
at least one medium to high frequency induction coil, and in that
on the outside of the thermal insulation there are provided a first
and a second tube element of material transparent to the induction
field of the medium to high frequency induction coil, which are
separated from each other by an annular gap, through which the
inert gas flows.
[0008] The heating device according to the invention uses, as its
heating source, a medium to high frequency induction coil. In the
frequency range of the induction coil, the thermal insulation used
according to the invention is transparent, i.e., an unwanted
dissipation of the induction field in the thermal insulation is
negligible.
[0009] Thanks to the fact that the inert gas in the heating device
according to the invention flows not only through the central
tubular induction heating element but also upstream from that
through the annular gap between the first and the second tube
element on the outside of the thermal insulation, an energy savings
is advantageously accomplished, because cold inert gas is heated in
said annular gap, so that it enters into the central tubular
induction heating element with a higher temperature and the desired
high temperature here, especially for the carbonization and/or
graphitization of the threadlike fiber starting material, is
achieved with an overall reduced energy input.
[0010] For the targeted guidance of the inert gas through the
annular gap between the first and the second tube element it has
proven to be advantageous to provide gas guiding elements in said
annular gap. The gas guiding elements can be guide ribs, knobs, or
the like. With the aid of the gas guiding elements, the dwell time
of the inert gas in the annular gap is increased in a defined
manner. The preheating or heating of the inert gas at the outlet
point from the annular gap is proportional to this increasing of
the dwell time.
[0011] It is especially helpful here for the inert gas to be guided
in counterflow through the annular gap between the first and the
second tube element and through the central tubular induction
heating element, i.e., for the inert gas to be directed through the
annular gap in one axial direction and in the central tubular
induction heating element in the axially opposite direction. This
counterflow guidance of the inert gas can be implemented in a
simple design manner.
[0012] An optimal carbonization and/or graphitization of the
threadlike fiber starting material can be achieved according to the
invention in that the inert gas is directed through the central
induction heating element in the one axial direction and at the
same time the threadlike fiber starting material is moved in the
opposite direction through the induction heating element.
[0013] The heating device according to the invention can be used to
move at least one fiber starting material thread through the
central tubular induction heating element. From the standpoint of
productivity, it is advantageous when the heating device according
to the invention is designed to move a number of fiber starting
material threads through the central induction heating element at
the same time, the fiber starting material threads lying spaced
apart from each other in one plane or in several planes. In such a
heating device of the last mentioned kind, the induction heating
element can have a round circular or an oval annular cross section.
Accordingly, the thermal insulation surrounding the central tubular
induction heating element can have an outer envelope surface which
is circular round or oval adapted to the oval annular cross
section.
[0014] It has proven to be advantageous in the heating device
according to the invention to use as the heating source a medium to
high frequency induction coil when the thermal insulation consists
of a carbon fiber felt. Likewise, it is possible according to the
invention for the thermal insulation to have an inner layer of a
carbon fiber felt and an outer layer of, for example,
Al.sub.2O.sub.3 fibers or of Al.sub.2O.sub.3/SiO.sub.2 fibers.
[0015] The efficiency of the heating device according to the
invention can be further improved in advantageous manner, i.e.,
increased, when the thermal insulation is spaced apart from the
central tubular induction heating element by an annular gap through
which a partial amount of the inert gas flows. The flow of the
inert gas occurs here in the aforementioned annular gap and the
flow of inert gas in the central tubular induction heating element
advisedly occurs in the same direction, i.e., in directions
parallel to each other.
[0016] At the two axially opposite ends of the central tubular
induction heating element and the first and second tube element of
the heating device according to the invention there is provided a
cover element each time. The two cover elements are placed
hermetically tight against the outside tube element.
[0017] It has proven to be advantageous in the heating device
according to the invention to provide the one cover element for the
diverting of the inert gas from the annular gap between the first
and the second tube element to the central tubular induction
heating element and the other cover element for the introducing of
the inert gas into the annular gap between the first and the second
tube element and for bringing the inert gas out from the central
tubular induction heating element.
[0018] An air lock for the threadlike fiber starting material being
carbonized and/or graphitized is preferably respectively provided
on each of the two cover elements on the outside.
[0019] The cover elements are advisedly each outfitted with a
cooling device. The coolant can be water, for example.
[0020] It is advantageous for the central tubular induction heating
element to consist of CFC (=carbon fiber-reinforced carbon). It is
especially advantageous for the carbon fibers used as the
reinforcement to be endless fibers.
[0021] At the two end sections facing away from each other axially
in the central tubular induction heating element there is advisedly
respectively provided a radiation shielding perforated disk in
order to minimize possible heat losses in the central tubular
induction heating element and consequently optimize the efficiency
of the heating device. It can be useful for the same purpose to
have provided in each case adjacent to the two end faces of the
thermal insulation facing away from each other axially at least one
radiation shielding annular disk.
[0022] The cover elements of the heating device according to the
invention can consist, for example, of aluminum, an aluminum alloy,
refined steel or the like. The cooling of the cover elements can
involve a water cooling, for example, as already mentioned.
[0023] It can be advantageous in the heating device according to
the invention to provide at least the first tube element adjacent
to the thermal insulation with an infrared reflecting coating on
the inside and/or the outside. The infrared reflecting coating can
be a full-surface or a partial coating. In the case of a partial
coating, this can be in the form of stripes, a lattice, spots or
the like.
[0024] Further details, features and benefits will emerge from the
following description of a sample embodiment of the heating device
according to the invention as shown schematically in the
drawing.
[0025] There is shown:
[0026] FIG. 1, in half-section, segment-wise, an embodiment of the
heating device, wherein the two cover elements axially facing away
from each other and axially spaced away from the self-supporting
central body of the heating device are shown partially cut
open,
[0027] FIG. 2, longitudinally cut on one side, another embodiment
of the central body of the heating device, and
[0028] FIG. 3, a representation similar to FIG. 2 of yet another
embodiment of the central body of the heating device.
[0029] FIG. 1 shows schematically a configuration of the heating
device 10 for producing carbon fibers from a threadlike fiber
starting material 12. The threadlike fiber starting material 12 is
a carbon-containing fiber material suitable for producing carbon
fibers, preferably a fiber material based on PAN
(=polyacrylonitrile).
[0030] Threadlike fiber starting material for producing carbon
fibers is oxidized in known manner in a first process step at
temperatures up to 400.degree. C., then carbonized at 400.degree.
C. to around 1600.degree. C. and then graphitized at 1600.degree.
C. to 2800.degree. C. The heating device according to the invention
is used in particular for the carbonization of the threadlike fiber
starting material. However, it will be understood that the heating
device according to the invention with proper dimensioning of the
at least one medium to high frequency induction coil can also be
used for the graphitization of the threadlike fiber starting
material. Optionally, a heating device according to the invention
can be used for the carbonization in combination with another
heating device according to the invention for the
graphitization.
[0031] Yet another option is to configure the heating device
according to the invention with multiple zones, i.e., to design the
medium to high frequency induction coil in multiple parts, where at
least one medium to high frequency induction coil is provided for
the carbonization and at least one other medium to high frequency
induction coil is provided for the graphitization of the threadlike
fiber starting material.
[0032] The heating device 10 has a central tubular induction
heating element 14, through which the threadlike fiber starting
material is moved. The direction of movement of the threadlike
fiber starting material 12 is indicated by the arrow 16.
[0033] The central tubular induction heating element 14 preferably
consists of CFC (=carbon fiber-reinforced carbon). It is especially
advantageous for the carbon fibers used as the reinforcement to be
endless fibers. Of course, other heat-resistant materials
inductively coupling the induction field of the medium to high
frequency induction coil, such as tungsten or the like, could also
be used. But as compared to materials of the latter mentioned kind,
CFC has the substantial advantage of a low procurement price.
[0034] The central tubular induction heating element 14 is
surrounded by a thermal insulation 18. The thermal insulation 18
consists of a carbon fiber felt 20.
[0035] Outside the thermal insulation 18 of carbon fiber felt 20,
there is provided an induction coil as the heating source, being a
medium to high frequency induction coil 22, which is operated for
example with a frequency of around 5 kHz to around 40 kHz, it being
understood that other frequencies can also be used. In the
frequency range employed, the thermal insulation 18 of carbon fiber
felt 20 is transparent to the induction field generated by the
induction coil 22, i.e., the coupling of the induction field in the
thermal insulation 18 is negligible.
[0036] The central tubular induction heating element 14 receives a
flow of an inert gas for the carbonization and/or graphitization of
the threadlike fiber starting material 12. This is indicated by the
arrows 24.
[0037] As is evident from FIG. 1, the inert gas is guided through
the central tubular induction heating element 14 in the one axial
direction as indicated by the arrows 24. At the same time, the
threadlike starting material 12 being carbonized and/or graphitized
is moved in the opposite direction as indicated by the arrow 16
through the central tubular induction heating element 14.
[0038] In order to achieve a heating device 10 with a comparatively
high efficiency according to the invention, a first tube element 26
is provided on the outside of the thermal insulation 18 and at a
radial spacing from this a second tube element 28, consisting of a
material transparent to the induction field of the induction coil
22. This material is, for example, quartz glass. It is also
possible for the first tube element 26 to consist of quartz glass,
for example, and the second tube element 28 of borosilicate
glass.
[0039] The two tube elements 26 and 28 are spaced apart from each
other by an annular gap 30. The inert gas flows through the annular
gap 30. In order to guide the inert gas flow in the annular gap 30
in a defined manner and in this way prolong the dwell time of the
inert gas in the annular gap 30, it has proven to be advantageous
to provide a number of gas guiding elements 32 in the annular gap
30. The gas guiding elements 32 consist advisedly of the same
material as the first and/or second tube element 28.
[0040] In the annular gap 30 the inert gas is heated by the
induction field of the medium to high frequency induction coil 22.
The heated inert gas is then introduced into the central space 34
of the tubular induction heating element 14. This is indicated in
FIG. 1 by the arc-shaped arrow 36. As is clearly seen, the inert
gas is guided through the annular gap 30 between the first and the
second tube element 26 and 28 in the one direction as indicated by
the arrow 38 and then through the central tubular induction heating
element 14 in the opposite direction as indicated by the arrows 24,
i.e., in counterflow.
[0041] In particular, when the heating device 10 according to the
invention is a heating device, for example, for a laboratory
facility or the like, the heating device 10 is provided for one
fiber starting material thread 12. In industrial use, the heating
device 10 is preferably designed so that a number of fiber starting
material threads 12 can be moved at the same time through the
central tubular induction heating element 14, the fiber starting
material threads 12 lying preferably at a spacing from each other
in at least one common plane or in several planes slightly spaced
apart from each other. This plane or these planes are perpendicular
to the plane of the drawing in FIG. 1.
[0042] The central tubular induction heating element 14 with the
thermal insulation 18, the first and the second tube element 26 and
28 and the medium to high frequency induction coil 22 form a
self-supporting central body 40 of the heating device 10, at whose
ends 42, 44 axially facing away from each other is provided one
cover element 46, 48 for each. The cover elements 46 and 48 are
only shown very schematically in FIG. 1 and spaced apart from the
central body 40. In the assembled state of the heating device 10,
the cover elements 46, 48 are hermetically sealed against the end
sections 50, 52 of the outside second tube element 28. This is
indicated by sealing bulges 54, 56, for example, with which the
cover elements 46, 48 are provided.
[0043] The cover element 46 is provided for diverting the inert gas
from the annular gap 30 between the first and the second tube
element 26, 28 to the central tubular induction heating element 14,
i.e., for diverting it into its central space 34, as indicated by
the arc-shaped arrow 36. For this purpose, the cover element 46 is
preferably designed with a deflection cavity for the inert gas (not
shown). The other opposite cover element 48 is provided for
introducing the inert gas into the annular gap 30 between the first
and the second tube element 26, 28 and for bringing the inert gas
out from the central space 34 of the central tubular induction
heating element 14. For this purpose, the cover element 48 likewise
only shown very schematically is provided with an inlet 58 for the
inert gas and an outlet 60 for bringing it out, while the cover
element 48 is likewise designed with partial cavities (not shown)
which are associated with the inlet 58 and the outlet 60.
[0044] The introducing of the inert gas into the cover element 48
is indicated by the arrow 62 and the bringing out of the inert gas
from the cover element 48 by the arrow 64.
[0045] On the outside of the cover element 46 is provided an air
lock 66 and on the outside of the cover element 48 an air lock 68
for the threadlike fiber starting material 12 being carbonized
and/or being graphitized or carbonized and/or graphitized. Each
cover element 46, 48 is respectively designed with a cooling system
70, which is a water cooling, for example. The reference number 72
designates a coolant inlet and the reference number 74 a coolant
outlet corresponding to the respective coolant inlet 72.
[0046] The respective cover element 46, 48 is provided on the
inside with a positioning and centering pin 76 slightly tapering as
a truncated cone, which in the assembled condition of the cover
elements 46, 48 with the central body 40 protrudes almost free of
play into the annular gap 30 between the first and the second tube
element 26, 28. The cover elements 46, 48 furthermore are provided
on the inside with positioning and centering pins 78, which
likewise interact free of play with the central tubular induction
heating element 14 in the assembled condition of the heating device
10.
[0047] In the central tubular induction heating element 14 at the
two end sections facing axially away from each other there is
provided a radiation shielding perforated disk 80 for each, in
order to localize the heat generated by the induction heating
element 14 in the central space 34. Next to each of the two end
faces 82 axially facing away from each other of the thermal
insulation 18 is placed at least one radiation shielding annular
disk 84. In FIG. 1, two radiation shielding annular disks 84 are in
each case shown at slight axial distance from each other.
[0048] At least the first tube element 26 next to the thermal
insulation 18 can be provided with an infrared reflecting coating
86 on the inside and or the outside. The reflecting coatings can be
full-surface or partial-surface. In the case of a partial coating,
this can be configured, for example, as stripes, a lattice, spots
arranged chaotically or in a grid.
[0049] The reference number 88 designates axially oriented strip
elements, by means of which the turns of the medium to high
frequency induction coil 22 are joined together and spaced apart
from each other in a defined manner.
[0050] FIG. 1 shows schematically an embodiment of the heating
device 10 in which the thermal insulation 18--as
mentioned--consists of a carbon fiber felt 20. On the other hand,
FIG. 2 shows in partial longitudinal sectioning an embodiment of
the central body 40 where the thermal insulation 18 has an inner
layer 90 and an outer layer 92. The inner layer 90 consists of a
carbon fiber felt 20 and the outer layer 92 of Al.sub.2O.sub.3
fibers, for example.
[0051] The same parts in FIG. 2 are designated with the same
reference numbers as in FIG. 1, so that it is unnecessary to
describe in detail once more all items in connection with FIG.
2.
[0052] FIG. 3 illustrates, in a half-sided longitudinal section
similar to FIG. 2, a feature of the self-supporting central body 40
of the heating device according to the invention. This embodiment
differs from the embodiment shown schematically in FIG. 2 in that
the thermal insulation 18 is spaced apart from the central tubular
induction heating element 14 by an annular gap 94, through which
the inert gas flows. This is indicated by the arrow 96.
[0053] The same parts in FIG. 3 are also designated with the same
reference numbers as in FIGS. 1 and 2, so that it is unnecessary to
describe in detail once more all items in connection with FIG.
3.
LIST OF REFERENCE NUMBERS
[0054] 10 Heating device (for 12) [0055] 12 Threadlike fiber
starting material [0056] 14 Central tubular induction heating
element (of 10) [0057] 16 Arrow/direction of movement (of 12)
[0058] 18 Thermal insulation (of 10 for 14) [0059] 20 Carbon fiber
felt (of 18) [0060] 22 Medium to high frequency induction coil (of
10 for 14) [0061] 24 Arrow/inert gas (for 12) [0062] 26 First tube
element (of 10) [0063] 28 Second tube element (of 10) [0064] 30
Annular gap (between 26 and 28) [0065] 32 Gas guiding elements (in
30) [0066] 34 Central space (of 14) [0067] 36 Arc-shaped arrow
(between 30 and 34) [0068] 38 Arrow (in 30) [0069] 40
Self-supporting central body (of 10) [0070] 42 End (of 40) [0071]
44 End (of 40) [0072] 46 Cover element (at 42) [0073] 48 Cover
element (at 44) [0074] 50 End section (of 28) [0075] 52 End section
(of 28) [0076] 54 Sealing bulge (of 46 for 50) [0077] 56 Sealing
bulge (of 48 for 52) [0078] 58 Inlet (at 48) [0079] 60 Outlet (at
48) [0080] 62 Arrow (between 58 and 30 in 52) [0081] 64 Arrow
(between 34 and 60) [0082] 66 Air lock (at 46, 48) [0083] 68 Air
lock (at 48, 48) [0084] 70 Cooling device (of 46, 48) [0085] 72
Coolant inlet (at 46 for 70) [0086] 74 Coolant outlet (at 46 for
70) [0087] 76 Positioning and centering pin (at 46, 48 for 32)
[0088] 78 Positioning and centering pin (at 46, 48 for 14) [0089]
80 Radiation shielding perforated disk (in 34) [0090] 82 End face
(of 18) [0091] 84 Radiation shielding annular disk (at 82) [0092]
86 Infrared reflecting coating (of 26 and/or 28) [0093] 88 Strip
element (of 22) [0094] 90 Inner layer (of 18) [0095] 92 Outer layer
(of 18) [0096] 94 Annular gap (between 14 and 18) [0097] 96 Arrow
(in 94)
* * * * *